1. Field of the Invention
The present invention relates to a disposable cutting insert, particularly to a cutting insert such as is adapted for being detachably mounted on a tool holder and for cutting a work piece. Cutting inserts of the present invention are generally made of a cemented metal carbide such as tungsten carbide and are formed by pressing techniques after which the pressed articles are sintered. The present invention particularly relates to such disposable cutting inserts for chip forming.
2. Description of Prior Art
In present day cutting operations such as in turning, facing, boring and contouring applications, the forming and breaking of the chip is an important consideration. In those operations utilizing disposable cutting inserts which have been formed by pressing and sintering it is known to provide chip forming configurations which are molded into a face of the insert. Various specific configurations are known including cutting inserts having grooves, dimples, depressions and the like.
The patent to Malaker et al, U.S. Pat. No. 4,626,141, is illustrative of a chip control insert embodying a chip control groove. The patent to Ohtsu et al, U.S. Pat. No. 3,815,192, is illustrative of a chip control insert embodying chip control dimples. The present invention relates to disposable cutting inserts for chip forming wherein a plurality of depressions have been molded into a top face thereof. Illustrative of this type of cutting insert are the inserts described in U.S. Pat. No. 4,215,957 to Holma et al; U.S. Pat. No. 4,273,480 to Shirai et al; U.S. Pat. No. 4,447,175 to Warren; and, U.S. Pat. No. 4,710,069 to Loqvist.
In the patent to Shirai et al, cutting inserts are provided having a plurality of intersecting recesses. Although such inserts may be useful in reducing friction and heat during use, such inserts do not provide adequate means to force the chips to curl and break as is desired during the cutting operation.
Warren and Loqvist provide for cutting inserts having spaced recesses which like Shirai et al are useful in reducing friction and heat during use. However, also like Shirai et al, the inserts of Warren and Loqvist do not provide adequate structure to cause the chips formed during the cutting operation to curl and break to the extent desired. In addition, the cutting inserts of Warren and Loqvist do not provide seating areas to allow for two sided use; that is, the structures described in Warren and Loqvist are one sided cutting inserts which can not be inverted for further use when one side is worn or damaged.
The patent to Holma et al describes cutting inserts having spaced recesses which like Shirai et al, Warren and Loqvist are also useful in reducing friction and heat during the cutting operation but provide less than adequate structure for curling and breaking chips during use. In addition, the spaced recesses of Holma et al intersect the periphery of the insert at its cutting edge which tends to diminish the strength of the edge.
It is highly desirable to provide an improved disposable cutting insert for chip forming. It is also desirable to provide a disposable cutting insert for chip forming wherein if a respective chip is not curled and broken along a first chip forming surface, a second surface is provided to effect such a result. It is likewise desirable to provide such structure including successive, gently sloping chip breaking surfaces. It is also desirable to provide such a cutting insert for chip forming having a positive rake surface on the upper surface of the insert. It is further desirable to provide a disposable cutting insert for chip forming having chip forming surface areas which reduce friction and heat while forcing chips to curl and break as desired during the cutting operation. It is also desirable to provide such structure having a plurality of spaced chip forming recesses wherein the strength of the cutting edges is not reduced by the presence of such recesses. It is highly desirable to provide such structure having opposing faces including opposing seating areas which allow for two sided use of the insert; that is, to provide such an improved insert which can be inverted from a first side to a second side when the first side is worn or damaged.